Heat exchangers of the type used for radiators in vehicle engine cooling systems or condensers in vehicle air conditioning systems utilize tubes carrying a coolant or refrigerant requesting that need to be cooled. The heat exchanger also commonly has fins, also called air centers, interposed between the tubes to effectively increase the contact with air for heat transfer to the air. The impetus for increasing the efficiency of heat exchangers is dictated by the need for more fuel efficient and aerodynamic motor vehicles.
The aerodynamic shape of many motor vehicles dictate that the hood line of the motor vehicle be lowered resulting in less space available in the engine compartment particularly in the vertical direction. Two of the largest components in the engine compartment are the radiator and condenser. The lower hood lines dictate for radiators or condensers with less core face area. Any decrease in core face area, overall size and weight of the radiator or condenser must therefor be accompanied by an increase in efficiency for heat transfer for a given air flow.
Often, louvers are incorporated in the fins to improve the heat transfer efficiency. Various fin and louver arrangements have been utilized to increase the heat transfer by increasing the turbulence of air about the fins and tubes. This increase in heat transfer is often accompanied by an undesirable increase in air pressure drop across the heat exchanger. It has also been found that various louver arrangements may be more advantageous than others. U.S. Pat. No. 4,693,307 issued to Scarselletta on Sep. 15, 1987, which is incorporated herein by reference, discloses a heat exchanger with fins having both louvered and non-louvered sections to have both low air pressure drop and high heat transfer performance at a constant air mass flow. U.S. Pat. No. 4,958,681 issued to co-inventor Durgaprasad S. Kadle, which is also incorporated herein by reference, discloses bypass channels positioned near the tube outer surface.
What is needed is an improved louver arrangement which improves efficiency over the teachings of the known prior art.